Update dependency / Remove grunt.util._

* I updated [`googleapis` module](https://github.com/google/google-api-nodejs-client/) to v0.6.1.
* I removed [`grunt.util._`](http://gruntjs.com/api/grunt.util#grunt.util._) because it is [deprecated](http://gruntjs.com/blog/2013-11-21-grunt-0.4.2-released).